1. Field of the Invention
The invention relates in general to elevator systems, and more specifically to hydraulic elevator systems having stabilizing arrangements for the hydraulic jack.
2. Description of the Prior Art
Hydraulic jacks of hydraulic elevator systems having a high slenderness ratio, and telescopic jacks, may require intermediate support to promote coaxial alignment of the cylinder and plunger, and thus prevent buckling.
When such intermediate support is necessary, the prior art teaches support arms which extend between the plunger, or plungers, and external guides, such as the elevator guide rails. For example, support arms may be actuated to sequentially move into engagement, at spaced intervals, with the plunger as the elevator car moves upwardly, and out of engagement, and thus out of the path of the elevator car, as the elevator car moves downwardly. Still other prior art arrangements teach support arms which automatically clamp to, and unclamp from, the plunger, such that they can be actuated to clamp to and move with the plunger when the ascending car reaches a predetermined height.
Co-pending U.S. Application Ser. No. 219,103, filed Dec. 22, 1980, entitled "Elevator System " discloses a new and improved hydraulic elevator system in which the hydraulic jack extends upwardly through the elevator car within an enclosed tunnel structure which extends from the lower beam of the car frame or sling to a predetermined point at or above the upper beam, in order to eliminate the need for drilling a hole in the ground for receiving the hydraulic jack. The upper end of the plunger contacts an end plate at the upper end of the tunnel. If more than about 16 feet of vertical travel is desired, the hydraulic jack would be of the telescopic type, if a hole for the jack is to be avoided. According to the prior art, stabilizer arms would be provided which would be actuated as the elevator car travels upwardly, which arms would extend from a plunger, or plungers of the telescopic hydraulic jack, to the elevator guide rails.